u have made a trunk port as port-fast. And the most easiest way of detection of loop (before the network goes down) is those flapping message you are getting. It does seems that your network is having a L2 loop.
Disable the port-fast (on both sides) and then see if you are getting the flapping message.
If you are brave enough, you can also apply bpdu-guard to the port-fast (if there is a loop, it will change the port to err-disable / shut).
Normally you would enable portfast on trunks with spanning-tree portfast trunk since regular spanning-tree portfast
We are pleased to announce availability of Beta software for 16.6.3.
16.6.3 will be the second rebuild on the 16.6 release train targeted
towards Catalyst 9500/9400/9300/3850/3650 switching platforms. We are
looking for early feedback from customers befor...
Introduction Featured Speakers Luis Espejel is the Telecommunications
Manager of IENova, an Oil & Gas company. Currently he works with Cisco
IOS® and Cisco IOS XE platforms, and NX to some extent. He has also
worked as a Senior Engineer with the Routing P...
In this session you can learn more about Layer 3 multicast and the best
practices to identify possible threats and take security measures. It
provides an overview of basic multicast, the best security practices for
use of this technology, and recommendati...